Franklin p



(No Model.)

F. P. LITTLE & W. H. MoDONALD.

RHBO STAT. No. 340,449. Patented Apr. 20, 1886.

M a /n/w o/aid WM 0 fiz-mfi UNITED STATES PATENT OFFICE.

FRANKLIN P. LITTLE AND WILLIAM H. MCDONALD, OF ALBANY, ASSIGNORS TO JOSEPH A. POWVERS, OF TROY, NEW" YORK.

RH EO STAT.

SPECIFICATION forming part of Letters Patent No 340,449, dated April 20, 1886.

Application filed January 22, 1886. Serial No. 189,355.

['0 all whom it may concern:

Be it known that we. FRANKLIN P. LITTLE and WILLIAM H. McDoNALD, of the city of Albany, and State of New York, have invented an Improvementin Rheostatsof which the following is a specification.

This invention relates to an improvement in rheostats,whereby naked wire can be made use of, and there is no covering that can be injured by the heat and the wire becomes cool very rapidly, and we provide insulating material that will not be injured by the heat developed by the resistance.

In the drawings, Figure 1 is a sectional plan of the rheostat without any case. Fig. 2 is a vertical section of the rheostat and case with only three coils of wire; and Fig. 3 is a sec tion in larger size, showing the insulating material.

We make use of a frame, K, in the form of crosses united together by the permanentlyrivetcd wires n,that pass from one cross to the other and through holes in the same, the ends being riveted up.

Ve prefer to use German'silver wire for the coils of the rheostat, and we wind such coils around the range of wires n, first, however, applying to each wire a a strip of asbestus paper or other fire-proof and electric insulator, as shown at t, Fig. 3, the wires being at aslight distance apart and insulated by the asbestus paper, which also is fire-proof (N0 modelJ and is not injured by the heat developed in the rheostat.

After the first layer of resistance-wire is 5 wound around the range of wires '11 and secured, we insert through holes in the crosses K the second set ofnvires, 0, and apply the asbestus paper to the same, and then wind the second layer of resistance-wires around the o san1e,and proceed until arheostatofthe proper resistance is made up, and this is placed upon a central stem, 1?.

The case T, that surrounds the rheostat is of perforatedsheet metal, to allow the air to cir- +5 culate in cooling the rheostat, and it is fast ened by pins or screws upon the edges of the base Q, entering bayonet slots in the case, so that the case can be removed easily to give access to the rheostat. 5o

\Ve claim as our invention Thecross-frames K, having connecting wires and fire-proofelectric insulating material upon their surfaces, in combination with the coils of wire wound around the ranges of connect- 5:, ing-wires, substantially as set forth.

Signed by us this 4th day of January, A. D. 1886.

F. P. LITTLE. \VM. H. MCDONALD.

Vitnesses:

R. E. Govn, J. H. KNIGHT. 

